The present invention relates to a hierarchical network management system, and relates more particularly to a hierarchical network management system which hierarchically manages network resources by agents, sub-managers and an integration manager and which uses SNMP (Simple Network Management Protocol) as a communication protocol among them.
In general, a management system of a communication network is structured by two types of sub-systems, managers and agents. A manager manages and controls network resources in agent unit. An agent manages and controls management objects such as structure information and status information in resource unit of the communication network.
There exist two international standards relating to management of communication networks, IAB (Internet Activities Board) management standard and OSI (Open Systems Interconnection) management standard. In the networks which use these management standards, their network resources are being managed in the following manner.
(1) Network management systems which use the management standard
When a communication network becomes large scale, the communication network is divided into a plurality of communication networks (hereinafter to be referred to as "sub-networks"), and a manager and agents are provided for each sub-network so that network resources of each sub-network are managed.
In this case, in carrying out resource management based on the IAB management standard, an SNMP (Simple Network Management Protocol) is used. The standard relating to the SNMP is prescribed by RFC 1157, "A Simple Network Management Protocol".
(2) Hierarchical network management system which uses both the OSI management standard and the IAB management standard
A sub-manager manages each LAN (Local Area Network) based on the IAB management standard, and the sub-manager and its higher level integration manager manages the network resources based on the OSI management standard, as described in "Integrated OSI Network Management for Distributed LAN Domains", Miyauchi et al., Information Processing Society of Japan, June 1993 issue, pp. 1426-1440, hereinafter to be referred to as "reference literature (1)".
Reference literature (1) proposes to achieve hierarchical network management by combining both the OSI management and the SNMP management. In other words, in this network, the sub-manager manages the network resources according to the IAB management standard, converts this management to management based on the OSI management standard and transfers the converted management to the integration manager. The integration manager then manages all of the resources of the network.
In managing a large-scale network, it is certainly effective to manage the network by a hierarchical structure from the viewpoint of deleting management packet and simplifying the manager.
However, no consideration is given to hierarchical management in the above-described network management system which uses the SNMP of the IAB management standard. Accordingly, even if a sub-manager is provided between the manager and the agents, it is not possible to achieve hierarchical management if the structure of management information to be transmitted between the manager and the sub-manager and the method for focusing the management information are not completed. In other words, one problem is that it is not possible to achieve a hierarchical network management system for managing and controlling a group of agents.
In this case, according to the standard of SNMPv2 (SNMP version 2), it is possible to notice an event from one manager to another manager. However, no consideration is given to hierarchical management in SNMPv2 as is the case with the SNMP. Accordingly, even if a sub-manager is provided between the manager and the agents, it is not possible to achieve the hierarchical management if the structure of management information to be transmitted between the manager and the sub-manager and the method for focusing the management information are not completed.
On the other hand, in the OSI management system described in reference literature (1), the sub-manager should have both communication service of the OSI standard for achieving the OSI management standard and communication service of the IAB standard for achieving the IAB management standard, so that there is a problem that the sub-manager becomes large in scale.
In the LAN, communication service of the IAB standard is used, and it is a normal application of the communication network that communication service of the IAB standard is used between LANs. Accordingly, in the management system described in reference literature (1), it is necessary to use the OSI management standard although the IAB management standard is used in a WAN (Wide Area Network). There is also a problem that the sub-manager is large in structure.
Further, when the integration manager hierarchically manages the communication network, which is managed by a plurality of management standards, by integrating the communication network, it is necessary to give advance consideration to the agency and distribution, etc., for reducing the load of conversion of management information and the load of the integration manager. However, no consideration is given to the agency, decentralization, etc., in management system of the reference literature (1). Therefore, there is a problem that, as the network becomes larger in scale, the number of management packets which are used at the time of exchanging management information between the integration manager and the sub-manager increases.